The present disclosure is related to a method and apparatus of horizontal drilling through earthen barriers. More specifically, the present disclosure is related to horizontal drilling through earthen barriers using a steerable drilling apparatus having a hammer drill powered by a mixture of air, oil, and water.
Underground bores that are oriented in a horizontal direction are used to route utilities through underground impediments such as rock structures. For example, an underground bore may be used to form a path for a utility line under a river bed. For example, U.S. Pat. No. 4,474,252 discloses an impact hammer positioned on the end of a rotating drill pipe. The air hammer is powered by compressed air which is mixed with lubricant to lubricate the hammer and water to flush the cuttings. The drill pipe is rotated at the machine and the mixture of air and water is produced at the machine with the mixture being introduced through a swivel connection to accommodate the introduction of the mixture into the rotating drill pipe.
U.S. Pat. No. 7,111,695 discloses pneumatic rock-boring device which is fed air and/or water through a single media channel allowing the device to be used with strings of drill pipe. The rock-boring device of U.S. Pat. No. 7,111,695 can be turned by the boring machine in a manner similar to the method used in the U.S. Pat. No. 4,474,252 to effect traditional drilling. Alternatively, the impact hammer may reciprocate thereby allowing the chisel to work material in contact with the rock-boring device. U.S. Pat. No. 7,111,695 also discloses that the rock-boring device may rotate while the chisel reciprocates.
U.S. Pat. No. 3,712,388 discloses a down-hole air hammer drill attached to rotatable drill pipe. The hammer drill of U.S. Pat. No. 3,712,388 has an air exhaust system that exhausts above the bit in the down hole to remove cuttings. The down-hole air hammer drill is used on a lower string of a drill pipe which rotated while the air hammer drill operates.
U.S. Pat. No. 6,659,202 discloses a steerable horizontal directional drilling system that rotates a fluid hammer and drill bit relative to the drill string. The drill head is continuously rotated relative to the drill string via a mud motor. The drill string is held stationary while the working end of the apparatus is rotated during the hammering to form the horizontal bore.